Display device including bending region including laminated first and second resin layers

ABSTRACT

The display device includes a substrate including a first resin layer, a second resin layer overlapping the first resin layer, and a first inorganic insulating layer between the first resin layer and the second resin layer, and having flexibility, a display region provided on the substrate, a terminal region arranged outside the display region on the substrate, and a bending region arranged between the display region and the terminal region. A thickness of the second resin layer is larger than a thickness of the first resin layer. The substrate includes a first region and a second region. The first resin layer, the first inorganic insulating layer, and the second resin layer are laminated in the first region. The first resin layer and the second resin layer are laminated in the second region and the first inorganic insulating layer is not laminated in the second region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/922,236 filed Jul. 7, 2020, and which is based upon and claims thebenefit of priority from the prior Japanese Patent Application No.2018-005057 filed on Jan. 16, 2018, and PCT Application No.PCT/JP2019/000518 filed on Jan. 10, 2019, the entire contents of each ofwhich are incorporated herein by reference.

FIELD

One embodiment of the present invention relates to a display device anda manufacturing method of the display device. One embodiment of thepresent invention relates to a flexible display device formed using aflexible substrate and a manufacturing method of the flexible displaydevice.

BACKGROUND

An example of display devices includes a liquid crystal display deviceand an organic electroluminescence (Electroluminescence: EL) displaydevice. These display devices include, in each of a plurality of pixelsformed on a substrate, a liquid crystal element or an organiclight-emitting element (hereinafter, the light-emitting element) as adisplay element. The liquid crystal element includes a layer containinga compound showing a liquid crystal property (hereinafter referred to asa liquid crystal layer) between a pair of electrodes, and thelight-emitting element includes a layer containing an organic compoundshowing an electroluminescence property (hereinafter referred to as anelectroluminescent layer or an EL layer). Then, the liquid crystalelement is driven by applying a voltage between the pair of electrodes,the light-emitting element is driven by passing a current.

In the aforementioned display device, by using a flexible substrate, itis possible to impart flexibility to the entire display device. Thisprovides a display device that is partially or wholly curved, or adisplay device that is freely deformable by the user. A region around adisplay region of the display device (hereinafter, also referred to as“peripheral region”, or “picture frame region”) by folding the substrateso as to be positioned toward the back side of the display region, toachieve a narrow frame display device is disclosed (e.g., Japaneselaid-open patent publication No. 2012-128006).

SUMMARY

A display device according to an embodiment of the present inventionincludes the display device includes a substrate including a first resinlayer, a second resin layer overlapping the first resin layer, and afirst inorganic insulating layer between the first resin layer and thesecond resin layer, and having flexibility, a display region provided onthe substrate, a terminal region arranged outside the display region onthe substrate, and a bending region arranged between the display regionand the terminal region. A thickness of the second resin layer is largerthan a thickness of the first resin layer. The substrate includes afirst region and a second region. The first resin layer, the firstinorganic insulating layer, and the second resin layer are laminated inthe first region. The first resin layer and the second resin layer arelaminated in the second region and the first inorganic insulating layeris not laminated in the second region. The first region overlaps thedisplay region and the second region overlaps the bending region.

A manufacturing method of display device according to an embodiment thepresent invention includes forming a first resin layer on a supportingsubstrate, forming a first inorganic insulating layer on the first resinlayer, removing a part of the first inorganic insulating layer so as toexpose a part of the first resin layer, forming a substrate on thesupporting substrate by forming a second resin layer on the firstinorganic insulating layer and the part of the first resin layer,forming a display region including pixels and a terminal regionincluding terminals outside the display region on the second resinlayer, forming a sealing film covering the display region, and peelingthe supporting substrate from the substrate. The part of the first resinlayer which is exposed by removing the part of the first inorganicinsulating layer includes a region between the display region and theterminal region.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic top view showing a display device according to anembodiment of the present invention;

FIG. 2 is a plan view showing a display device according to anembodiment of the present invention;

FIG. 3 is a plan view showing a display device according to anembodiment of the present invention;

FIG. 4 is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 5 is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 6A is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 6B is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 6C is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 7 is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 8 is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 9 is a cross-sectional view showing a display device according toan embodiment of the present invention;

FIG. 10A is a cross-sectional view showing a manufacturing method of adisplay device according to an embodiment of the present invention;

FIG. 10B is a cross-sectional view showing a manufacturing method of adisplay device according to an embodiment of the present invention;

FIG. 100 is a cross-sectional view showing a manufacturing method of adisplay device according to an embodiment of the present invention; and

FIG. 10D is a cross-sectional view showing a manufacturing method of adisplay device according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

One of object of one embodiment of the present invention is to provide adisplay device capable of maintaining high reliability even when asubstrate having flexibility is bent or curved.

Hereinafter, in each embodiment of the present invention will bedescribed with reference to the drawings and the like. However, thepresent invention may be implemented in various modes without departingfrom the gist of the technical idea thereof and is not construed asbeing limited to the description of the embodiments exemplified below.

The drawings may be schematically represented in terms of width,thickness, shape, and the like of each part as compared with actualembodiments for the sake of clarity of description, but are merelyexamples, and the illustrated shape itself is not intended to limit theinterpretation of the present invention. In the drawings, elementshaving the same functions as those described with reference to thedrawings already described in the specification are denoted by the samereference numerals even in other drawings, and overlapping descriptionsare omitted in some cases.

In the present invention, in the case where one film is processed toform a plurality of films, the plurality of films may have differentfunctions or roles, and each structure may have a different base film onwhich it is formed. However, the plurality of films is derived from thefilm formed in the same step as the same layer, and have the same layerstructure and are formed of the same material. Therefore, the pluralityof films is defined as being present in the same layer.

In expressing a mode of arranging another structure on a certainstructure, the case of simply expressing “above” includes both the caseof arranging another structure directly above a certain structure incontact with the structure and the case of arranging another structureabove the certain structure through another structure, unless otherwisespecified.

The phrase “one structure is exposed from another structure” means aregion in which a portion of one structure is not covered by anotherstructure. However, this includes the case where a portion not coveredby the other structure is covered by still another structure.

Embodiment 1

Referring to FIG. 1 to FIG. 8 , the structure of a display device 100according to an embodiment of the present invention will be described.

FIG. 1 is a schematic top view of the display device 100. The displaydevice 100 has a substrate 101, on one surface of the substrate 101 isprovided with various conductive layers, semiconductor layers, andinsulating layers patterned to the desired shape. Using these conductivelayers, semiconductor layers, and insulating layers, a plurality ofpixels 103 is formed. Driving circuits (a gate driver circuit 104 and asource driver circuit 105) for driving the plurality of pixels 103 maybe formed on the substrate 101 simultaneously with the plurality ofpixels 103 using the above-described conductive layers, semiconductorlayers, and insulating layers, or an IC chip may be mounted on onesurface of the substrate 101. The plurality of pixels 103 is arranged,for example, in a matrix, and a display region 102 is formed by thesesets.

The gate driver circuit 104 and the source driver circuit 105 arelocated on a peripheral region 770 of the display region 102. From thedisplay region 102, the gate driver circuit 104, and the source drivercircuit 105, various wirings (not shown) formed of patterned conductivelayers extend to one side of the substrate 101. Each wiring is connectedto one of a plurality of terminals 106 located near an end portion ofthe substrate 101. A region that contains the plurality of terminals 106is also known as a terminal region. The plurality of terminals 106 isconnected to a flexible printed circuit board 107 (Flexible PrintedCircuit: FPC). If the aforementioned driving circuit is provided by theIC chip, it may be mounted on the flexible printed circuit board 107rather than on the substrate 101.

Video signals and various control signals are supplied through theflexible printed circuit board 107 from a controller (not shown)provided outside the display device 100. The video signals are processedby the source driver circuit 105 and input to the plurality of pixels103. Various control signals are input to the gate driver circuit 104,and the source driver circuit 105.

In addition to the video signals and the various control signals, powerfor driving the gate driver circuit 104, the source driver circuit 105,and the plurality of pixels 103 is supplied to the display device 100.Each of the plurality of pixels 103 has the light-emitting element to bedescribed later. A part of the power supplied to the display device 100is supplied to the respective light-emitting element of the plurality ofpixels 103 to cause the light-emitting element to emit light.

By using the substrate having flexibility as the substrate 101, it ispossible to impart flexibility to the display device 100 as shown inFIG. 2 to FIG. 4 . For example, as shown in FIG. 2 , a bendable region200 is provided over the entire display region 102, it can be applied tohighly designable electronic devices the display region 102 is curvedsurface shaped. The display device 100 may be applied to an electronicdevice in which the display region 102 is stored in a roll-like shape.

As shown in FIG. 3 and FIG. 4 , the substrate 101 is provided with abending region 300 between the display region 102 and the flexibleprinted circuit board 107. By bending the substrate 101 in the directionof an arrow 301 in the bending region 300 so as to overlap the sourcedriver circuit 105 and the flexible printed circuit board 107 on a backsurface side of the display region 102, it is possible to reduce theframe size of the display device 100.

FIG. 4 is a cross-sectional view taken along A-A′ line shown in FIG. 3 .The substrate 101 can be folded as indicated by the arrow 301. Thus, thesource driver circuit 105 and the flexible printed circuit board 107 arearranged so as to overlap the back surface side of the display region102. Therefore, the display device 100 can be narrowed frame asindicated by a width 302. Inside the folded portion, a spacer 303 may beprovided to retain the cross-sectional form of the substrate 101.

<Structure of the Substrate 101>

FIG. 5 is a cross-sectional view of the display device 100 according toan embodiment of the present invention. FIG. 5 shows an enlarged view ofa part of the display device. In the display region 102, the substrate101 has a stacked structure including a first resin layer 501, a firstinorganic insulating layer 502, an inorganic material layer 503, and asecond resin layer 504. In the display region 102, a functional layer505 including a plurality of pixels formed using the conductive layer,the semiconductor layer, and the insulating layer is formed on thesubstrate 101, a sealing film 506 is formed on the functional layer 505.In the bending region 300, the substrate 101 has a stacked structure ofthe first resin layer 501 from which the first inorganic insulatinglayer 502 and the inorganic material layer 503 have been removed and thesecond resin layer 504.

As the first resin layer 501 and the second resin layer 504, forexample, an organic resin such as acrylic, polyimide, polyethyleneterephthalate, or polyethylene naphthalate can be used. The first resinlayer 501 and the second resin layer 504 may be layers using the samematerial or layers using different materials.

Inorganic materials such as a silicon oxide, a silicon nitride, or asilicon oxynitride can be used as the first inorganic insulating layer502. By providing the first inorganic insulating layer 502 between thefirst resin layer 501 and the second resin layer 504, it is possible toprevent moisture and other contaminants from entering the functionallayer 505 from the first resin layer 501 through the second resin layer504.

The inorganic material layer 503 is provided between the first inorganicinsulating layer 502 and the second resin layer 504. As the inorganicmaterial layer 503, for example, a layer containing silicon such assilicon oxide or amorphous silicon can be used. The resin layer and theinorganic insulating layer differ in the stresses remaining in the filmdue to the differences in their materials and the process of formingthem. As a result, the adhesion at the interface between the two isdeteriorated. The deterioration of the adhesion is particularlyconspicuous when the resin layer is formed on the inorganic insulatinglayer. Therefore, in this embodiment, by providing the inorganicmaterial layer 503 having good adhesion to both of the first inorganicinsulating layer 502 and the second resin layer 504, adhesion betweenfirst inorganic insulating layer 502 and the second resin layer 504 canbe improved. Although not shown, as the substrate 101, a structure maybe employed in which the inorganic material layer 503 is providedbetween the first inorganic insulating layer 502 and the second resinlayer 504, and the inorganic material layer is further provided betweenthe first resin layer 501 and the first inorganic insulating layer 502.As the substrate 101, the inorganic material layer 503 between the firstinorganic insulating layer 502 and the second resin layer 504 may beomitted, and the inorganic material layer may be provided between thefirst resin layer 501 and the first inorganic insulating layer 502.

However, when the substrate 101 is folded, the presence of the inorganicinsulating layer in the bending region 300 causes cracks in theinorganic insulating layer. The cracks in the inorganic insulating layercause moisture and other contaminants to enter the functional layer 505from the cracks. If moisture or contaminants that have entered thefunctional layer 505 enter the light-emitting element in the pixel, thelight-emitting element may be degraded. This may reduce the reliabilityof the display device.

Therefore, the display device 100 according to the present embodimenthas the stacked structure including the first resin layer 501, the firstinorganic insulating layer 502, the inorganic material layer 503, andthe second resin layer 504 in at least the display region 102 of thesubstrate 101. The substrate 101 has, in the bending region 300, astacked structure of the first resin layer 501 from which the firstinorganic insulating layer 502 and the inorganic material layer 503 havebeen removed and the second resin layer 504.

The substrate 101, in the display region 102, the first inorganicinsulating layer 502 and the inorganic material layer 503 are providedbetween the first resin layer 501 and the second resin layer 504. Thus,it is possible to prevent moisture and other contaminants from enteringthe functional layer 505 from the first resin layer 501 through thesecond resin layer 504. In the bending region 300, the first inorganicinsulating layer 502 and the inorganic material layer 503 between thefirst resin layer 501 and the second resin layer 504 have been removed.As a result, in the bending region 300, since a stacked structure isformed between the first resin layer 501 and the second resin layer 504,the bending resistance of the substrate 101 can be improved.

<Manufacturing Method of the Substrate 101>

Next, a manufacturing method of the substrate 101 will be described byreferring to FIG. 6A to FIG. 6C.

FIG. 6A is a diagram illustrating a process of forming the first resinlayer 501, the first inorganic insulating layer 502, and the inorganicmaterial layer 503 on a support substrate 1001. First, a resin materialsuch as acrylic, polyimide, polyethylene terephthalate, or polyethylenenaphthalate is formed on the support substrate 1001 by a coating method,and then a first heat treatment is performed. Thus, the first resinlayer 501 can be formed. Next, the first inorganic insulating layer 502is formed of the silicon oxide, the silicon nitride, or the siliconoxynitride on the first resin layer 501 by a vapor phase growth methodsuch as a CVD method. A thickness of the first inorganic insulatinglayer 502 is preferably 20 nm or more and 100 nm or less. Thereafter,the inorganic material layer 503 is formed of silicon oxide or amorphoussilicon by the CVD method. A thickness of the inorganic material layer503 is preferably 5 nm or more and 20 nm or less. As the inorganicmaterial layer 503, amorphous silicon is preferably used.

FIG. 6B is a diagram illustrating a process of removing the firstinorganic insulating layer 502 and the inorganic material layer 503 inthe bending region 300. A mask is formed on a region other than thebending region 300 on the first inorganic insulating layer 502 and theinorganic material layer 503, and the first inorganic insulating layer502 and the inorganic material layer 503 of the bending region 300 areremoved by an etching process.

FIG. 6C is a diagram illustrating a process of forming the second resinlayer 504 on the display region 102, the bending region 300, and theterminal 106. On the inorganic material layer 503 and the first resinlayer 501, a resin material such as acrylic, polyimide, polyethyleneterephthalate, or polyethylene naphthalate is formed by the coatingmethod, and then a second heat treatment is performed. Thus, the secondresin layer 504 can be formed.

By the above process, the substrate 101 can be formed.

In the first heat treatment and the second heat treatment at the time offorming the first resin layer 501 and the second resin layer 504, gascomponents are desorbed from the first resin layer 501 and the secondresin layer 504. For example, during the second heat treatment to formthe second resin layer 504, the gas components are also desorbed fromthe first resin layer 501. However, since the first inorganic insulatinglayer 502 is formed on the first resin layer 501, the desorbed gascomponents stay in the vicinity of the interface between the first resinlayer 501 and the first inorganic insulating layer 502. As a result,peeling may occur at the interface between the first resin layer 501 andthe first inorganic insulating layer 502. This desorption of the gascomponents occurs in a larger amount with a larger volume of the firstresin layer 501. Therefore, in this embodiment, the volume is reduced byreducing the film thickness of the first resin layer 501 to be smallerthan the film thickness of the second resin layer 504, and thedesorption of the gas components from the first resin layer 501 isformed to be as small as possible.

In the present embodiment, as shown in FIG. 5 , the thickness of thefirst resin layer 501 is preferably smaller than the thickness of thesecond resin layer 504. For example, it is preferable that the filmthickness of the first resin layer 501 is set to 70% or less, preferablyabout 40% to 60% of the film thickness of the second resin layer 504.Specifically, the thickness of the first resin layer 501 is about 50% ofthe thickness of the second resin layer 504.

The film thickness of the substrate 101 is preferably a thickness thatachieves both flexible enough to be bent or folded as shown in FIG. 2 toFIG. 4 and strong enough not to cause breakage by bending. The substrate101 includes the above-mentioned stacked structure, and the filmthickness of the substrate 101 may be, for example, 100 μm or less,preferably 50 μm or less. More preferably, the film thickness of thesubstrate 101 is about 10 μm to 30 μm. The film thickness of the secondresin layer 504 is sufficiently larger than the film thickness of thefirst inorganic insulating layer 502 and the film thickness of theinorganic material layer 503. Therefore, the film thickness of thesubstrate 101 of the region from which the first inorganic insulatinglayer 502 and the inorganic material layer 503 have been removed iswithin the above-mentioned film thickness range, and the film thicknessof the substrate 101 of the region from which the first inorganicinsulating layer 502 and the inorganic material layer 503 have not beenremoved is within the above-mentioned film thickness range.

The first resin layer 501 and the second resin layer 504 arerespectively baked at about 450° C. to 500° C. In this embodiment, themaximum value of the second heat treatment of the second resin layer 504is set so as not to exceed the maximum value of the first heat treatmentof the first resin layer 501. As described above, in the second heattreatment of the second resin layer 504, the first resin layer 501 isalso heated at the same time, but the desorption of the gas componentsfrom the first resin layer 501 is small unless the maximum value of thebaking temperature is reached when the first resin layer 501 is baked inadvance. Temporarily, at the time of the second heat treatment of thesecond resin layer 504, when exceeding the maximum value of thetemperature of the first heat treatment of the first resin layer 501,since the first resin layer 501 has no heating history thereof,desorption of the new gas components occurs. Therefore, by setting themaximum value of the temperature of the second heat treatment of thesecond resin layer 504 so as not to exceed the maximum value of thefirst heat treatment temperature of the first resin layer 501, it ispossible to suppress the desorption of the gas components from the firstresin layer 501 during the second heat treatment of the second resinlayer 504.

<Structure of the Display Device>

The structure of the display device 100 according to the presentembodiment will be described referring to FIG. 7 and FIG. 8 .

FIG. 7 is a cross-sectional view taken along B-B′ line of the displaydevice 100 shown in FIG. 1 . FIG. 7 mainly shows the display region 102including a transistor structuring the pixel, the terminal 106, and abending region 750 for folding the peripheral region 770 including theterminal 106.

As described above, the substrate 101 has the first resin layer 501, thefirst inorganic insulating layer 502, the inorganic material layer 503,and the second resin layer 504. In the bending region 750 of thesubstrate 101, the first inorganic insulating layer 502 and theinorganic material layer 503 have been removed. An undercoat layer 701is provided on the substrate 101. In FIG. 7 , the undercoat layer 701has a three-layer structure of a first layer 701 a, a second layer 701b, and a third layer 701 c. By providing silicon oxide as the firstlayer 701 a, the adhesion of the substrate 101 to the second resin layer504 can be improved. By providing the silicon nitride as the secondlayer 701 b, moisture and other contaminants from the outside can beblocked. By providing silicon oxide as the third layer 701 c, hydrogenatoms contained in the silicon nitride of the second layer 701 b can beprevented from diffusing into a semiconductor layer 706 contained in thefunctional layer 505. The undercoat layer 701 is not limited to theabove structure, and may be a single layer structure or a double layerstructure, or may be a stacked structure of four or more layers.

The undercoat layer 701 may be provided with a light shielding layer 702in accordance with a portion where the transistor is to be providedlater. The light shielding layer 702 can suppress a change in transistorproperty due to the penetration of light from a back surface of thechannel of the transistor or the like. If the light shielding layer 702is a conductive layer, the light blocking layer 702 can function as aback gate which controls the threshold value of the transistor byapplying a predetermined potential. In FIG. 7 , a light shielding layer702 is provided in an island shape over the first layer 701 a so as tocorrespond to a portion where a transistor is formed. A second layer 701b and a third layer 701 c are stacked on the light shielding layer 702.The undercoat layer 701 is provided so as to enclose the light shieldinglayer 702. One embodiment of the present invention is not limitedthereto, and the light shielding layer 702 may be provided on thesubstrate 101, and the first layer 701 a, the second layer 701 b, andthe third layer 701 c may be provided thereon as the undercoat layer701.

The transistor is provided on the undercoat layer 701. The transistorhas the semiconductor layer 706, a gate insulating film 704, and a gateelectrode 705. As the semiconductor layer 706, amorphous silicon,polysilicon, or an oxide semiconductor can be used. As the gateinsulating film 704, the silicon oxide or the silicon nitride can beused. As the gate electrode 705, titanium, molybdenum, tungsten, or thelike can be used. The gate electrode 705 also functions as a storagecapacitor line. In other words, the semiconductor layer 706, the gateinsulating film 704, and the gate electrode 705, it is possible to forma storage capacitor 707.

The transistor shown in FIG. 7 is a drive transistor and is an Nch typetransistor. The Nch type transistor has a structure in which a lowconcentration impurity region is provided between a channel region and asource region or a drain region (high concentration impurity region). Asthe transistor, here, although only the Nch type transistor is shown, aPch type transistor may be provided together with the Nch typetransistor.

An interlayer insulating layer 708 is provided on the transistor. As theinterlayer insulating layer 708, a silicon nitride film or a siliconoxide film can be used. The interlayer insulating layer 708 has acontact hole that reaches the semiconductor layer 706. The interlayerinsulating layer 708 is formed with the contact hole, and at the sametime, the interlayer insulating layer 708 and the gate insulating film704 at a point corresponding to the bending region 750 are also removed.Furthermore, by removing the interlayer insulating layer 708 and thegate insulating film 704, since the undercoat layer 701 is exposed,which is also removed by patterning. After the undercoat layer 701 isremoved, the second resin layer 504 constituting the substrate 101 isexposed. At this time, though not particularly shown, the surface of thesecond resin layer 504 may be partially eroded through the etching ofthe undercoat layer 701 to cause film reduction.

A conductive layer 709 serving as a source electrode, a drain electrode,and a routing wiring is provided on the interlayer insulating layer 708.As the conductive layer 709, a three-layer stacked structure oftitanium, aluminum, and titanium can be used. A part of the storagecapacitor 707 is formed using the interlayer insulating layer 708, anelectrode formed of a conductive layer in the same layer as the gateelectrode 705 of the transistor and an electrode formed of a conductivelayer in the same layer as the source/drain wiring of the transistor.The routing wiring extends to an end portion of a peripheral of thesubstrate 101. The routing wiring constitutes the terminal 106 thatconnects the flexible printed circuit board 107 and the driver IC. Theterminal 106 may be formed of the conductive layer of the same layer asthe gate electrode 705.

A planarization film 710 is provided to cover the transistor and therouting wiring. As the planarization film 710, an organic material suchas photosensitive acrylic or polyimide can be used. The organic materialis superior in flatness to an inorganic insulating material formed bythe CVD or the like.

The planarization film 710 is partially removed in the pixel contactportion and the peripheral region 770. The portion where the conductivelayer 709 is exposed by removing the planarization film 710 is coveredwith a transparent conductive film 711. For example, an ITO (Indium tinoxide) is used as the transparent conductive film 711. On thetransparent conductive film 711 is covered with an inorganic insulatinglayer 712. As the inorganic insulating layer 712, the silicon nitridecan be used. Then, a pixel electrode 713 is formed by opening theinorganic insulating layer 712 in the pixel contact portion. Here, thepixel electrode is formed as a reflective electrode, is a three-layerstacked structure of IZO, Ag, IZO. In a pixel portion, an additionalcapacitance 714 is formed by the transparent conductive film 711, theinorganic insulating layer 712, and the pixel electrode 713. On theother hand, the transparent conductive film 711 is also formed on thesurface of the terminal 106. The transparent conductive film on theterminal 106 is provided as a barrier film so that the exposed portionof the wiring is not damaged in the subsequent processes.

Incidentally, when patterning the pixel electrode 713, a part of thetransparent conductive film 711 is exposed to the etching gas. However,by an annealing process performed between the formations of thetransparent conductive film 711 to the pixel electrode 713, thetransparent conductive film 711 is sufficiently resistant to the etchingprocess of the pixel electrode 713.

On the pixel electrode 713, an insulating layer called a bank 715, whichis serving as a barrier of a pixel region is provided. As the bank 715,an organic material such as photosensitive acrylic or polyimide is usedas in the case of the planarization film 710. The bank 715 is preferablyopened to expose the surface of the pixel electrode 713 as alight-emitting region, and an edge of the opening is preferably a smoothtapered shape. If the edge of the opening is a steep sharp, a coveragedefect of the organic layer provided on the bank 715 occurs.

The planarization film 710 and the bank 715 have a portion in contactwith each other through an opening 716 provided in the inorganicinsulating layer 712. The portion is an opening for drawing the moistureand the gas desorbed from the planarization film 710 through the bank715 through the heat treatment or the like after the bank 715 is formed.Here, moisture and the gas to be desorbed are the same phenomena asthose to be desorbed from the first resin layer 501 and the second resinlayer 504 at the time of forming the substrate 101 described above. Byevolving the desorbed moisture and gas from the planarization film 710to the bank 715 through the opening 716, peeling the interface betweenthe planarization film 710 and the inorganic insulating layer 712 can besuppressed.

An organic layer 717 including the organic EL layer is provided on thepixel electrode 713 and the bank 715. In FIG. 7 , although the organiclayer 717 is shown as a single layer, a hole transport layer, alight-emitting layer, and an electron transport layer are stacked inthis order from the pixel electrode 713. These layers may be formed byvapor deposition or may be formed by a coating of solvent dispersion. Asshown in FIG. 7 , the organic layer 717 may be selectively provided foreach pixel or may be provided solidly on the entire surface covering adisplay region 760. When the organic layer 717 is provided solidly, astructure is employed that obtains white light in all the pixels andextracts a desired color wavelength portion by a color filter (notshown).

A counter electrode 718 is provided on the organic layer 717. In thepresent embodiment, since a top emission structure is employed, thecounter electrode 718 needs to be optically transparent. The topemission structure is a structure in which light is emitted from thecounter electrode 718 disposed on the substrate 101 with the organiclayer 717 interposed therebetween. Here, as the counter electrode 718,an MgAg film is formed as a thin film to the extent that the emittedlight from the organic EL layer is transmitted. According to the orderof forming the organic layer 717 described above, the pixel electrode713 side becomes the anode, the counter electrode 718 side becomes thecathode. The counter electrode 718 is formed over the display region 760and a cathode contact portion 780 provided in the vicinity of thedisplay region 102, is connected to the lower layer of the conductivelayer 709 at the cathode contact portion 780, and is ultimately drawnout to the terminal 106.

A sealing film 719 is provided on the counter electrode 718. The sealingfilm 719 can prevent moisture from entering the organic layer 717 fromoutside. The sealing film 719 is required to have a gas barrierproperty. Here, a stacked layer structure of an inorganic insulatinglayer 719 a, an organic insulating layer 719 b, and an inorganicinsulating layer 719 c is shown as a stacked structure including thesilicon nitride film as the sealing film 719. Although not shown inparticular, a silicon oxide film or an amorphous silicon film may beprovided as the inorganic material layer between the inorganicinsulating layer 719 a and the organic insulating layer 719 b asdescribed in the stacked layer step of the substrate 101.

As shown in FIG. 8 , a cover member 800 is provided on the sealing film719 via an adhesive member 810.

According to the display device shown in the present embodiment, thesubstrate 101 is formed so that the thickness of the second resin layer504 is larger than the thickness of the first resin layer 501. Thus,desorption of the gas components from the first resin layer 501 isreduced as much as possible. The maximum value of the temperature at thetime of the heat treatment of the second resin layer 504 is set so asnot to exceed the maximum value of the temperature at the time of theheat treatment of the first resin layer 501. Thus, the desorption of thegas components from the first resin layer 501 during baking of thesecond resin layer 504 can be suppressed. As a result, peeling at theinterface between the first resin layer 501 and the first inorganicinsulating layer 502 can be suppressed.

As the substrate 101, the first inorganic insulating layer 502 isprovided between the first resin layer 501 and the second resin layer504. By providing the first inorganic insulating layer 502, it ispossible to suppress moisture and other contaminants from entering thefunctional layer 505 through the first resin layer 501 and the secondresin layer 504. The inorganic material layer 503 is provided betweenthe first resin layer 501 and the first inorganic insulating layer 502or between the first inorganic insulating layer 502 and the second resinlayer 504. As a result, the adhesion between the first resin layer 501and the first inorganic insulating layer 502 or between the firstinorganic insulating layer 502 and the second resin layer 504 can beimproved.

In the display device 100 shown in this embodiment, the first inorganicinsulating layer 502 and the inorganic material layer 503 between thefirst resin layer 501 and the second resin layer 504 are removed in thebending region 750. As a result, in the bending region 750, the firstresin layer 501 and the second resin layer 504 are in stacked structurewith each other, so that the bending resistance of the substrate 101 canbe improved. In the bending region 750, the inorganic insulating layerincluded in the functional layer 505 and the sealing film 506 as well asthe first inorganic insulating layer 502 and the inorganic materiallayer 503 included the substrate 101 has been removed. Therefore, forsecuring the strength of the bending region, to cover the bending region750, a resin coating 820 or the like may be provided on the conductivelayer 709. As the resin coat 820, for example, it is preferable to useTUFFY manufactured by Hitachi Chemical Company.

Embodiment 2

Another embodiment of the display device of the present invention willbe described with reference to FIG. 9 .

In FIG. 7 , the structure in which the inorganic insulating layer (theundercoat layer 701, the gate insulating film 704, and the interlayerinsulating layer 708) provided on the upper layer than the substrate 101is removed in the bending region 750 has been described. FIG. 9 shows astructure in which the first inorganic insulating layer 502 and theinorganic material layer 503 are also removed in the terminal 106. Asshown in FIG. 9 , after removing the interlayer insulating layer 708 andthe undercoat layer 701, the second resin layer 504 may be subsequentlyremoved.

As a result, it possible to form the substrate 101 in which the firstinorganic insulating layer 502 and the inorganic material layer 503 arenot provided in the bent region 750 and the terminal 106. The conductivelayer 709 is provided to be in contact with the first resin layer 501.In one embodiment, the bending region 750 after removing the secondresin layer 504 has a lower mechanical strength because the filmthickness of the first resin layer 501 is thinner than that of thesecond resin layer 504. Therefore, it is very effective to provide theresin coat 820 in the bending region as shown in FIG. 8 .

According to the structure of the display device shown in the presentembodiment, the substrate 101 can be favorably bent by the structure inwhich the first inorganic insulating layer 502 and the inorganicmaterial layer 503 do not extend in the bending region 750 and theterminal 106. In the bending region 750, the mechanical strength of thebending region 750 can be improved by providing the resin coat 820 afterthe substrate 101 is bent. Thus, it is possible to provide the displaydevice capable of maintaining a high reliability even if curved or bentthe substrate 101 having flexibility.

Embodiment 3

In the present embodiment, a method of forming the substrate 101 to thesealing film on the support substrate 1001 and then peeling the upperlayer of the substrate 101 from the support substrate will be describedreferring to FIG. 10A to FIG. 10D.

When the substrate 101 is made of a material having flexibility, it isdifficult for the substrate 101 to maintain flatness through the stepsshown in FIG. 7 to FIG. 9 . Therefore, when forming the display devicehaving flexibility, first of all, it is preferable to form the substrate101 to the sealing film 506 on the support substrate 1001.

As shown in FIG. 10A, the substrate 101, the display region 102 providedwith the plurality of pixels having the transistor and thelight-emitting element, the terminal region located the outside of thedisplay region 102, and the bending region between the display region102 and the terminal region are formed on the support substrate 1001.

Glass, quartz, or the like can be used as the support substrate 1001.The substrate 101 including the first resin layer 501, the firstinorganic insulating layer 502, the inorganic material layer 503, andthe second resin layer 504 is formed on the support substrate 1001. Asdescribed in the first embodiment, in the bending region 750 of thesubstrate 101, the first inorganic insulating layer 502 and theinorganic material layer 503 are removed so that the first resin layer501 is in contact with the second resin layer 504. As shown in FIG. 9 ,in the terminal region where the terminal 106 is provided, the firstinorganic insulating layer 502 and the inorganic material layer 503 maybe removed and the first resin layer 501 may be in contact with thesecond resin layer 504.

The thickness of the first resin layer 501 is preferably smaller thanthe thickness of the second resin layer 504. For example, it ispreferable that the film thickness of the first resin layer 501 is setto 70% or less, preferably about 40% to 60% of the film thickness of thesecond resin layer 504. Specifically, the film thickness of the firstresin layer 501 is about 50% of the film thickness of the second resinlayer 504. The first heat treatment is performed for the first resinlayer 501, and the second heat treatment is performed for the secondresin layer 504. At this time, the maximum value of the second heattreatment of the second resin layer 504 is set to be lower than themaximum value of the first heat treatment of the first resin layer 501.Thus, at the time of the second heat treatment of the second resin layer504, it is possible to suppress the gas components desorption from thefirst resin layer 501. Therefore, it is possible to suppress stagnationof the desorbed gas components between the first resin layer 501 and thefirst inorganic insulating layer 502. As a result, peeling of the filmfrom between the first resin layer 501 and the first inorganicinsulating layer 502 can be suppressed.

Next, the functional layer 505 including the display region 102 and thegate driver circuit 104 in which the plurality of pixels formed usingthe conductive layer, the semiconductor layer, and the insulating layerare provided is formed on the substrate 101.

The undercoat layer 701 including the first layer 701 a, the secondlayer 701 b, and the third layer 701 c is formed on the substrate 101.The light shielding layer 702 may be formed on the first layer 701 a.

By forming the semiconductor layer 706 and the gate insulating film 704,and the gate electrode 705 on the undercoat layer 701, form thetransistor. In the same layer as the gate electrode 705, a conductivelayer for forming the storage capacitor together with a semiconductorlayer 703 is also formed at the same time. Next, the interlayerinsulating layer 708 is formed on the gate electrode 705. The contacthole is formed on the interlayer insulating layer 708, and at the sametime, the interlayer insulating layer 708, the gate insulating film 704and the undercoat layer 701 corresponding to the bending region 750 areremoved.

The conductive layer 709 which functions as the source electrode, thedrain electrode, and the routing wiring is formed on the interlayerinsulating layer 708. A part of the storage capacitor 707 can be formedusing an interlayer insulating layer 708, an electrode formed of aconductive layer in the same layer as the gate electrode 705 of thetransistor, and an electrode formed of a conductive layer in the samelayer as the source/drain wiring of the transistor. The routing wiringis formed to extend to the end portion of the periphery of the substrate101. The routing wiring forms the terminal 106 that connects theflexible printed circuit board 107 and the driver IC. The terminal 106may be formed of the conductive layer of the same layer as the gateelectrode 705.

The planarization film 710 is formed on the conductive layer 709. Then,the planarization film 710 is removed at the pixel contact portion and apart of the peripheral region 770. The portion where the conductivelayer 709 is exposed by removing the planarization film 710 is coveredwith the transparent conductive film 711. Next, the inorganic insulatinglayer 712 is formed on the planarization film 710 and the transparentconductive film 711.

The inorganic insulating layer 712 is opened at the pixel contactportion and the opening 716. Next, the pixel electrode 713 is formed onthe inorganic insulating layer 712. The pixel electrode 713 is connectedto the transparent conductive film 711 via the opening of the pixelcontact portion. Then, the bank 715 is formed to cover the edge portionof the pixel electrode 713. At this time, the bank 715 has opened sothat the surface of the pixel electrode 713 exposed as thelight-emitting region, and the opening edge is formed to be a smoothtapered shape.

The organic layer 717 including the organic EL layer is formed on thepixel electrode 713 and the bank 715. As the organic layer 717, the holetransport layer, the light-emitting layer, and the electron transportlayer are stacked in order from the pixel electrode 713 sides. Next, thecounter electrode 718 is formed on the organic layer 717. Thelight-emitting element can be formed by the pixel electrode 713, theorganic layer 717, and the counter electrode 718.

Next, as shown in FIG. 10B, the sealing film 506 having the inorganicinsulating layer 719 a, the organic insulating layer 719 b, and theinorganic insulating layer 719 c is formed on the functional layer 505.The sealing film 506 is preferably formed so that the inorganicinsulating layer 719 a and the inorganic insulating layer 719 c are incontact with each other in the end portion of the display region 760.This prevents moisture from entering the functional layer 505 from theend portion of the display region 760.

Through a series of processes for forming the substrate 101 to thesealing film 506 shown in FIG. 10A and FIG. 10B, maintaining theflatness of the substrate 101 by the support substrate 1001, so that themanufacturing processes including high-precision photolithography can beperformed normally.

Subsequently, as shown in FIG. 100 , a laser irradiation process 1002 isperformed from the side of the surface where the substrate 101 of thesupport substrate 1001 has not formed. By the laser irradiatingtreatment 1002, a part 1003 of the first resin layer 501 of thesubstrate 101 in contact with the support substrate 1001 isdeteriorated, and the adhesiveness is lowered. This decrease in adhesionis brought by the first resin layer 501 being partially ablated orshrunk by heat.

Thereafter, as shown in FIG. 10D, a physical force is applied betweenthe support substrate 1001 and the substrate 101 to peel off at theinterface therebetween. The display device 100 peeled from the supportsubstrate 1001 can form the display device 100 as shown in FIG. 2 toFIG. 4 by the flexibility of the substrate 101.

After the process shown in FIG. 10D, fold the substrate 101 in thebending region 750. Then, the resin coat 820 as shown in FIG. 8 may beformed to enhance the strength of the bending region 750. Finally, byattaching the cover member 800 via the adhesive member 810, the displaydevice shown in FIG. 8 can be formed.

According to the manufacturing method of the display device shown inthis embodiment, since the flatness on the substrate 101 havingflexibility is maintained, it is possible to perform the high-precisionphotolithography. Thus, the semiconductor layer, the insulating layer,and the conductive layer can be processed with high precision.

Within the scope of the present invention, it is understood that variousmodifications and amendments can be made by those skilled in the art,and that these modifications and amendments also fall within the scopeof the present invention. For example, as long as the gist of thepresent invention is provided, a person skilled in the art who adds,deletes, or changes the design of components or adds, omits, or changesthe conditions of processes to each of the above-described embodimentsis included in the scope of the present invention.

What is claimed is:
 1. A display device comprising: a substrateincluding a first resin layer, a second resin layer overlapping thefirst resin layer, and a first inorganic insulating layer between thefirst resin layer and the second resin layer, and having flexibility; adisplay region provided on the substrate; a terminal region arrangedoutside the display region on the substrate; and a bending regionarranged between the display region and the terminal region, wherein athickness of the second resin layer is larger than a thickness of thefirst resin layer, the substrate includes a first region and a secondregion, the first resin layer, the first inorganic insulating layer, andthe second resin layer are laminated in the first region, the secondregion includes the first resin layer, the second resin layer and thefirst inorganic insulating layer are not laminated in the second region,the first region overlaps the display region and the second regionoverlaps the bending region, and the first resin layer is in directcontact with the second resin layer in the terminal region.
 2. Thedisplay device according to claim 1, wherein the second region overlapsthe terminal region.
 3. The display device according to claim 2, whereinthickness of the first resin layer is 70% or less of thickness of thesecond resin layer.
 4. The display device according to claim 3, furthercomprising: an inorganic material layer provided between the first resinlayer and the first inorganic insulating layer or between the firstinorganic insulating layer and the second resin layer.
 5. The displaydevice according to claim 4, wherein the first inorganic insulatinglayer includes silicon nitride.
 6. The display device according to claim5, wherein the inorganic material layer includes silicon oxide oramorphous silicon.
 7. The display device according to claim 6, furthercomprising: a second inorganic insulating layer provided on thesubstrate; a semiconductor layer provided on the second inorganicinsulating layer; a third inorganic insulating layer provided on thesemiconductor layer; and a gate electrode overlapping the semiconductorlayer on the third inorganic insulating layer, wherein the second regionincludes a third region in which the first resin layer does not overlapthe second inorganic insulating layer and the third inorganic insulatinglayer.
 8. The display device according to claim 7, further comprising: afourth inorganic insulating layer provided on the third inorganicinsulating layer in the first region, an organic insulating layerprovided on the fourth inorganic insulating layer, and a fifth inorganicinsulating layer provided on the organic insulating layer, wherein thefourth inorganic insulating layer is in contact with the fifth inorganicinsulating layer in an edge of the first region, and the second regionincludes a fourth region in which the first resin layer does not overlapthe fourth inorganic insulating layer and the fifth inorganic insulatinglayer.